1. Field of the Invention
The present disclosure relates generally to downhole tools useful in operations related to oil and gas exploration, drilling and production. More particularly, embodiments of the disclosure relate to a chemical injection valve operable to automatically move to a closed configuration before the hydrostatic pressure in a chemical supply line may be diminished.
2. Background
In operations related to the production of hydrocarbons from subterranean geologic formations, chemical management can be important in optimizing fluid productions as well as minimizing well downtime and expensive intervention. For example, chemicals may be injected into various locations of a wellbore to inhibit certain processes like corrosion or the accumulation of scale. Also, certain chemicals may be introduced into a wellbore to treat the production fluids to alter their chemical properties in the downhole environment, e.g., to reduce viscosity or other fluid characteristic.
In a typical chemical injection installation, a chemical injection mandrel is interconnected into a production tubing string and includes an injection port positioned at the desired location. For example, the injection port may be positioned to permit flow into an interior of the tubing string at a particular depth, or alternatively, the injection port may be positioned to permit flow into down-hole locations exterior to the tubing string. One or more chemicals may be supplied to the chemical injection mandrel through a chemical supply line that extends from a chemical pumping unit disposed at a surface location. Various control and communication lines may also extend between the mandrel and surface control equipment to facilitate operation of down-hole components on the mandrel. A check valve may be positioned between the chemical supply line and injection port to discourage wellbore fluids, such as production gas oil or water from migrating into the chemical injection system upstream of the check valve.
Also, it is common for sacrificial rupture discs to be provided within the chemical supply line upstream of the injection port to permit pressure testing of the chemical supply line prior to operation. The rupture discs may be rated to withstand pressures of the desired testing, and may be ruptured to permit fluid flow to the injection port once the testing is complete.
It has been found that in various instances, a chemical injection pressure maintained by the chemical pumping unit in the chemical supply line may be inadvertently diminished. For example, depletion of the production fluids from a wellbore interval may affect the ability to maintain the hydrostatic pressure, or alternatively failure of the chemical pumping unit may result in an uncontrolled draining of the chemicals in the chemical supply line through the injection port. The diminishment of hydrostatic pressure may cause hydrates to form that can plug the chemical supply lines.